Electronically commutated motor driven apparatus

ABSTRACT

An apparatus for pumping fluid such as an integral pump/motor is provided. A housing having an inlet and an outlet has a rotatable assembly including an impeller located within and adapted to rotate within the housing to move fluid through the housing from the inlet to the outlet. Secured to the exterior of the housing is a stationary assembly for applying an electromagnetic field through the housing to and around the impeller to rotate the impeller and thereby to cause it to move fluid through the housing. 
     The apparatus is for use in a cooling system, such as a cooling system of an automobile engine, to pump fluid through the cooling system. A temperature sensor is provided for sensing the temperature of the fluid within the cooling system. An electronic control, responsive to the temperature sensor, supplies electrical power to stationary assembly. 
     Also, a method of circulating fluid within a system, such as a cooling system of an automobile engine, is disclosed. An electromagnetic field is applied through a housing to and around a rotatable assembly including an impellar located in the housing thereby to axially rotate the impeller and cause it to move fluid through the housing.

This application is a division of U.S. patent application Ser. No.07/160,526, filed Feb. 26, 1988, now U.S. Pat. No. 4,876,492.

FIELD OF THE INVENTION

The invention relates generally to dynamoelectric machines that utilizeelectronic commutation means and, more particularly, such machinesintegral with an apparatus to be driven such as a pump.

BACKGROUND OF THE INVENTION

Electronically commutated motors have been used to drive various typesof apparatus, such as pumps, by directly or indirectly coupling a shaftextending from the rotor assembly of the motor to the drive shaft of thepump. As the piston or impeller of the pump is in contact with the fluidto be pumped a fluid seal is needed around the pump drive shaft orextension thereof to prevent fluid leakage. Such fluid seals generallyrequire maintenance and wear with use thus increasing the likelihood offluid leakage.

One of the most widely used types of pump is the automotive "water"(antifreeze/coolant) pump in which a pulley keyed to a shaft carryingthe pump impeller is driven by the automobile engine via a belt andpulley coupling. Such pumps require fluid seals around the pump shaftwhich present a significant maintenance problem. Existing conventionalwater pumps tend to have the seals and bearings fail long before otherengine components. A significant factor in such failures is the sideload on bearings and seals from the belt and pulley drive, and thistends to allow pressurized coolant to leak out of the system and causebearing seizure. Replacement costs in both labor and parts is high.

As such pumps can only operate when the engine is operating, pumping ofthe fluid through the cooling system ceases when the engine stopsresulting in sharply rising engine block temperatures from the heatbeing built up in the fluid within the block. There is a concommitantand excessive under-hood temperature increase, particularly intransverse mounted engines, front wheel drive automobiles and otherengines which have high operating temperatures to reduce hydrocarbon andcarbon monoxide emissions. Increased under-hood temperaturessignificantly reduce the useful life of rubber and plastic parts in theengine compartment.

Additionally, such pumps always operate when the engine is operatingthereby requiring thermostatic valves to control fluid flow within thecooling system. Thermostatic valves inhibit fluid flow until the fluidreaches operating temperature so that the engine and fluid surroundingit quickly reach the optimum operating temperature.

SUMMARY OF THE INVENTION

Among the several objects of the invention may be noted the provision ofa new and improved integral electronically commutated motor/pump for usein pumping fluid, such as the coolant in an automobile engine coolingsystem; the provision of such an integral motor/pump which avoids theneed for fluid seals around rotating shafts; and in which nounsymmetrical or side loads must be carried by rotating shafts; theprovision of an automotive "water" pump which can be selectivelyoperated during and subsequent to engine operation thereby providingcoolant flow which is independent of engine operation, reduces sharplyrising engine block temperature when the engine is first turned off andis responsive to the temperature of the fluid within the cooling systemthereby eliminating the need for a thermostat, a high maintenance item;the provision of an integral axial flow, variable output, permanentmagnet, electronically commutated motor driven automotive "water" pumpwith pumping parts made of synthetic resin so that the pump islightweight and can be located at various points within the coolingsystem and operates at a low noise level; the provision of an integralpump/motor for use in an automotive cooling system which will circulateonly the amount of coolant through the engine and radiator necessary tomaintain the system operating temperature within a specified range; theprovision of such an integral pump/motor for automotive cooling systemswhich is economical in cost, reliable in operation and has reducedreplacement cost; and the provision of an improved method forcirculating coolant through an automobile engine cooling system.

These as well as other objects and advantageous features will be in partapparent and in part pointed out hereinafter.

In general, in one form of the invention apparatus for pumping fluid isprovided which includes a housing having an inlet and an outlet andmeans, located within and adapted to rotate within the housing, formoving fluid through the housing from the inlet to the outlet. Securedto the exterior of the housing are means for applying an electromagneticfield through the housing to and around the fluid moving means to rotatethe fluid moving means and thereby to cause it to move fluid through thehousing.

Also, in general, in another form of the invention apparatus for pumpingfluid is provided which comprises a motor having a rotor assembly and astator assembly. Housing means, having a fluid inlet and a fluid outletbetween which an axis is defined, encloses the rotor assembly. Thestator assembly is located on and surrounds the housing. Means forapplying electrical power to the stator assembly are provided so thatthe stator assembly applies an electromagnetic field through the housingto and around the rotor assembly thereby to rotate the rotor assemblyabout the axis. Means driven by the rotor assembly and located withinthe housing axially pumps the fluid from the inlet to the outlet as therotor assembly rotates about the axis.

Generally, and in still another form of the invention, an electronicallycommutated motor is provided which includes a rotatable assembly havingan axis and which is supported for rotation about the axis by meanswhich includes a housing surrounding the rotatable assembly. Astationary assembly having a plurality of winding stages surrounds thehousing and are adapted, when electrically energized, to apply anelectromagnetic field to the rotatable assembly to cause the rotatableassembly to rotate about the axis.

In general, in a further form of the invention, an electronicallycommutated motor is provided which comprises a rotatable assembly havingan axis and including a cylindrical ferromagnetic member having an axialopening coaxial with the axis wherein the axial opening is adapted toreceive an element to be rotated, such as an impeller. The assembly alsoincludes a plurality of permanent magnet elements peripherally securedto the ferromagnetic member. Means coaxial with the axial opening of theferromagnetic member support said rotatable assembly for rotation aboutthe assembly axis. A stationary assembly having a plurality of windingstages surrounds said means. The winding stages are adapted to beelectrically energized to apply an electromagnetic field to saidrotatable assembly to cause the rotatable assembly to rotate about theassembly axis.

Generally, in a still further form of the invention, an apparatus foruse in a cooling system, such as a cooling system of an automobileengine, to pump fluid through the cooling system is provided. Theapparatus includes a housing having an inlet and an outlet adapted to beconnected in the cooling system. First means, located within and adaptedto rotate within the housing, move fluid within the cooling system fromthe inlet to the outlet. Means are also provided for sensing thetemperature of the fluid within the cooling system. Second means securedon the housing applies an electromagnetic field through the housing toand around the first means thereby to rotate the first means and causeit to move fluid through the housing from the inlet to the outlet.Means, responsive to said temperature sensing means, supply electricalpower to said second means.

Also in general, and in accordance with this invention, a method ofcirculating fluid within a system, such as a cooling system of anautomobile engine is provided. A rotatable assembly including animpeller is located within a housing which is connected in the system.An electromagnetic field is applied through the housing to and aroundthe rotatable assembly thereby to axially rotate the impeller and causeit to move fluid through the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects of the present invention and their attendant advantageswill become readily apparent from the following description taken inconjunction with the accompanying figures in which like referencecharacters are used to describe like parts throughout the several views:

FIG. 1 is an exploded, perspective view of the main elements of anintegral pump/motor embodying teachings of the present invention in oneform thereof;

FIG. 2 is a diagrammatic front elevational view of the laminations ofthe stator assembly of the FIG. 1 pump/motor illustrating its rotatableassembly in cross section;

FIG. 3 is a longitudinal, cross sectional view of the integralpump/motor according to the invention;

FIG. 4 is a perspective view of an assembled integral pump/motor of theinvention;

FIG. 5 is a graphical representation of the relationship of torque inounce-feet (oz-ft) along the x-axis versus thousands of revolutions perminute (KRPM) along the y-axis of an integral pump/motor according tothe invention; and

FIG. 6 is a block diagram of an engine cooling system employing theintegral pump/motor of this invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Referring now to the drawings, and more particularly to FIG. 1, anapparatus for Pumping fluid such as a pump integral with and driven by abrushless DC motor, i.e., an electronically commutated motor, adapted tobe energized from an electrical power source is shown and generallyreferred to by reference character 1. The integral pump/motor 1 includesa stationary assembly 10a, 10b including core or stator assembly 11 anda rotatable assembly 20 including a permanent magnet rotor assembly 21.The rotor assembly 21 is coaxially supported for rotation about its axis22 by impeller 27 and shaft 23. The shaft 23, journaled for rotation inand supported by bearings 12a, 12b (see FIG. 3) in inlet end cap 13a andoutlet end cap 13b, is coaxial with axis 22. The rotor assembly 21 issurrounded by and rotatable within the bore 14a of a tubular core orhousing 14 which provides a fluid passageway having an inlet 15 and anoutlet 16. The end caps 13a, 13b are partially located within the inlet15 and outlet 16, respectively, and are sealed to the tubular housing 14by conventional means. For example, in one preferred embodiment it iscontemplated that housing 14 and end caps 13a and 13b are made of asynthetic resin ("plastic") in which case the end cap 13a may beinductively sealed to the inlet 15 of tubular housing 14 by an inductivetype (Emabond) inlet ring seal 17 and the end cap 13b may be similarlyinductively sealed to the outlet 16 of housing 14 by ring seal 18. Endcaps 13 and shaft 23 constitute means coaxial with the assembly axis 22for supporting the rotatable assembly 20 for rotation about its axis.

Rotor assembly 21 comprises a low reluctance core such as aferromagnetic core in the form of a cylindrical, ferromagnetic memberhaving an axial opening or bore 26 coaxial with the assembly axis 22.The member, generally referred to as backiron 24, is surrounded by anumber of thin flat annular ferromagnetic elements or laminationssecured to the outer peripheral surface of backiron 24 so as toestablish constant magnetic polar regions with North-Southpolarizations. Four essentially identical relatively thin arcuatesegments 25a, 25b, 25c, 25d of permanent magnet material (e.g., ceramictype, cobalt samarium, Alnico, Magnequench MQ 1, etc.), each providing arelatively constant flux field, are peripherally secured (for example,by adhesive bonding) to backiron 24. The segments 25 each spanapproximately 90 mechanical degrees and are magnetized to be polarizedradially in relation to the backiron 24 with adjacent segments beingalternately polarized to provide constant magnetic polar regions. Forexample, the outer surfaces of segments 25a and 25c may be northpolarized, as partially indicated, and the outer surfaces of segments25b and 25d may be south polarized, with the inner surfaces oppositelypolarized. While segments 25 on backiron 24 are illustrated for purposesof disclosure, it is contemplated that other rotor assemblies havingdifferent constructions and other magnet elements different in bothnumber, contruction and flux fields may be utilized with such otherrotor assemblies within the scope of the invention so as to meet atleast some of the objects thereof.

Backiron 24 has an axial opening therein with an axis coaxial with therotor assembly axis 22. The axial opening defines a backiron bore 26within which impeller 27 is positioned. Impeller 27 includes a centrallylocated, longitudinal opening coaxial with the rotor assembly axis 22forming a bore within which shaft 23 is positioned. Impeller 27 issecured within the bore 26 of backiron 24, for example, by press-fittingor adhesive bonding. Rotatable assembly 20 including shaft 23, impeller27 and the rotor assembly 21 (backiron 24 and segments 25a-d) constitutemeans located within and adapted to rotate within a housing, such as 14,for moving fluid through the housing from the inlet 15 to the outlet 16.

Referring to FIGS. 2 and 3, stator assembly 11 may be fabricated of acore of thin ferromagnetic laminations 51, as is conventional in the ACmotor art, which are held together by retainer clips positioned innotches (not shown) around the outer periphery of the laminations 51.Alternatively, the stator laminations may be held together by suitablemeans, such as for instance welding or adhesively bonding, or merelyheld together by the windings 53, all as will be understood by thoseskilled in the art. Six inwardly directed poles 55 define the statorbore 57 and six winding stages 53 disposed around the poles 55 areadapted to be selectively commutated. Winding stages 53 surround and arecarried by housing 14 and are adapted to be electrically energized toapply an electromagnetic field to the rotatable assembly 20 to cause itto rotate about its axis 22. As a result, the rotatable assembly 20 isassociated with the stationary assembly 10 in selective magneticcoupling relation with the winding stages 53 so as to be rotatablydriven thereby. The winding terminal ends or leads (not shown) arebrought out and connected separately to a control system such as a threephase, half bridge control circuit as disclosed in U.S. Pat. Nos.4,169,990 and 4,532,459, incorporated herein by reference. While statorassembly 11 is illustrated for purposes of disclosure, it iscontemplated that other stator assemblies of various other contructionshaving different shapes such as stators having various numbers of polesand slots therebetween may be utilized within the scope of the inventionso as to meet at least some of the objects thereof.

The stator assembly 11 and rotor assembly 21 comprise an electronicallycommutated motor, such as a brushless DC motor or the like for instance.For purposes of disclosure, motor 1 is illustrated as a three stage,salient, six pole, brushless, DC motor but it will be understood thatthe motor of this invention may be a distributed wound or salient motorof 2, 4, 8, etc. pole construction and have 2, 3, 4 or more windingstages within the scope of the invention to meet at least some of theobjects thereof. Stator assembly 11 including laminations 51 and windingstages 53 constitute means secured to the exterior of a housing such as14 for applying an electromagnetic field through the housing to andaround the rotatable assembly 20 to rotate it and thereby cause it tomove fluid through tubular housing 14. Housing 14 is formed of anon-magnetic material such as a synthetic resin to permit theelectromagnetic field to pass therethrough. In order to protect thestator assembly 11 from dirt and dust, a cover 59a, 59b having two clamshell-like portions which fit together may be used to surround thestator assembly 11.

As shown in FIGS. 2 and 3, impeller 27 constitutes means for pumpinglocated in the axial opening (bore 26) cf backiron 24 and comprises acylindrical member 61 having a plurality of four internal radial vanes63 extending helically along the axis 22. From the inlet end 65 ofmember 61 to the outlet end 67 of member 61, the surface of eachhelical, radial vane 63 axially rotates through an angle ofapproximately 45 mechanical degrees (also shown by the dotted line 37 onthe surface of impeller 27 illustrated in FIG. 1). Impeller 27 rotateson axis 22 as part of the rotatable assembly 20 due to the angular forceimparted onto magnetic segments 25 by the electromagnetic fieldgenerated by the selective commutation of the winding stages which areenergized from an electrical power source. Such rotation of the impeller27 in the direction of arrow 30 propels fluid within the impeller andthe end caps 13a, 13b in the direction of arrow 31. The propelling ofthe fluid results from the forces exerted on the fluid by the surfacesof the helical radial vanes 63.

This force may impart a helical motion to the fluid which, in someapplications, may be undesirable. Accordingly, end caps 13a and 13b maybe comprised of cylindrical members 34a, 34b having internal, axiallyextending radial vanes 35 which axially straighten the fluid motion andtend to inhibit helical motion of the fluid. Also, vanes 35 provideradial strength and rigidity to the end caps 13a, 13b so that, forexample, a hose or other conduit of a fluid line may be clamped over theend caps thereby permitting the pump/motor to be positioned in a fluidline such as the hose connections of a cooling system as discussedbelow.

Means are provided coaxial with the axial opening of backiron 24 forsupporting the rotatable assembly 20 for rotation about its axis 22. Inparticular, internal radial vanes 63 of the cylindrical member 61 definea bore coaxial with the rotatable assembly axis 22 within which shaft 23is positioned. The internal axially extending radial vanes of eachcylindrical member 34a, 34b of the end caps 13a, 13b also define a borecoaxial with the axis 22 within which bearing means such as brassbearing assemblies 64a, 64b for supporting each end of the shaft 23 ispositioned.

Furthermore, the cylindrical members 34a, 34b of end caps 13a, 13b mayinclude a circumferential flange 66 for engaging the ends of thecylindrical member or extrusion 14. In order to seal the endcaps to theextrusion, a seal such as inductive inlet seal 17 and inductive outletseal 18 are located between the flange 66 and the end of the extrusion.Inductive seals are generally synthetic resin mixed with metallicparticles which are heated by a varying magnetic flux field. Ifinductive seals are employed, the seals are inductively heated whichfuses the seals and creates a bond between the end cap and flange.Casing such as cover 59a, 59b may be provided to cover the stationaryassembly 10.

For automotive applications, it is contemplated that one preferredembodiment of the invention would have laminations 51 with a diameter ofapproximately 3.2" so that the gap between the stator bore 57 andsegments 25 would be approximately 0.1". These dimensions permit the endcaps to have an outside diameter of approximately 1.75" for engaging ahose to have a wall thickness of somewhat less than 0.1".

FIG. 4 illustrates the fully assembled integral pump/motor 1 accordingto the invention. Cover 59a, 59b is shown surrounding stator 11 whichhas housing 14 (not visible in FIG. 4) so located within the stator borethat end caps 13a and 13b project from either side of the cover.Rotatable assembly 20 is located within the bore of housing 14.

In one preferred embodiment of the invention, it is contemplated thatthe segments 25 have a radial height of 0.15" and a length of 0.88",that the impeller 27 have a wall thickness of 0.08", that the stackedlaminations have a width of 0.75", that the resistance of two coils perphase of the windings (each having 37 turns of 0.0339 copper wire) havea resistance of 0.2 ohms per phase and an inductance of 470 microhenrysper phase, and that the no load speed equal 6000 RPM. Position sensingof the rotor assembly 11 would be by sensing the back EMF and thecontrol circuit would be a three phase, half bridge. In this embodimentthe flux density of the air gap has been measured to be 0.34 tesla and,as illustrated in FIG. 5, the design load at 3000 RPM (approximately 5gallons per minute) is approximately 2.2 oz-ft for a 12.8 volt DC powersupply and 2.6 oz-ft for a 14.0 volt DC power supply. Such a motor wouldhave a K_(E) equal to 0.0020 volts per RPM.

Referring to FIG. 6, the integral pump/motor 1 according to theinvention is shown in block diagram form for use in a cooling system foran engine 100 to pump fluid through the cooling system. For example,engine 100 may be a fluid-cooled, gasoline powered, piston engine suchas an automobile engine having a fluid jacket 102 surrounding the engineblock to cool the engine block by absorbing heat generated within theblock by the operation of engine. In this preferred embodiment theintegral pump/motor 1 performs the function of an automotive "water"(fluid) pump. Fluid 104, such as water or an antifreeze/coolant such asethylene glycol which is within the cooling system, is heated by theheat generated by operation of engine 100. The heated fluid 104 is movedfrom the water jacket 102 through fluid line 106 to radiator 108 wherethe fluid is cooled by the air which passes through the radiator. Cooledfluid 110 flows through fluid line 112 to integral pump/motor 1 whichpumps the cooled fluid 110 back into the water jacket 102 via line 114.The system may also include a bypass line 116 between lines 112 and 106with inline valve 118 for controlling the flow of recirculated heatedfluid 104. Valve 118 may be used to control the amount of heated fluid104 flowing through the bypass line 116. The cooling system may beprovided with one or more lines for providing auxiliary flow of thefluid. For example, heated fluid 104 may be provided to a carburetor topreheat the air/fuel mixture or to heat the automatic choke valve. Also,the auxiliary flow may be part of a passenger compartment heating systemof an automobile in which case heated fluid is directed through a heatexchanger in the passenger compartment. When the integral pump/motor 1is operating, it pumps fluid from its inlet 120 to its outlet 122creating a pressure differential which causes fluid within the system tocirculate.

Generally, radiator 108 is a heat exchanger well known in the prior art.The radiator 108 includes a plurality of fluid channels in contact withfins over which air passes. The fluid is pumped through the channels bythe pressure differential created by the operation of the integralpump/motor 1. Air passes through the radiator and over the fins as theradiator moves through the air as part of a vehicle, or air can bepulled through the radiator by fan blades 124 which are rotated by thefan motor 126. Electronic control 128 controls the operation of the fanmotor 126 in response to means for sensing the temperature of the fluidwithin the cooling system. For example, the temperature of the heatedfluid 104 as sensed by temperature sensor 130 may be used to control theoperation of the fan motor 126. Such sensors are well known in the priorart and may be thermocouples, thermistors, or any other sensing devicein contact with the fluid which provides a signal to electronic control128 indicative of temperature of the fluid being monitored. Suchcontrols are also well known in the prior art. For example, if thetemperature of the heated fluid is higher than a certain desiredmaximum, say 240° F., electronic control 128 would activate fan motor126 to rotate fan blades 124. This results in air flowing in thedirection of arrows 134 over the fins of the radiator 108 therebycooling the fluid within the channels of the radiator. Control 128 wouldoperate fan motor 126 until the temperature differential becomes greaterthan the desired minimum or the temperature of the heated fluid fallsbelow the desired maximum Control 128 constitutes means responsive tothe temperature sensing means for supplying electrical power to thestator assembly of integral pump/motor 1. Presently, such a temperaturesensor is located in the cylinder head of an automobile to measurecoolant temperature therein. An electronic control in the form of amicroprocessor that controls the emission control system and the fanmotor operation in response to the measured temperature It iscontemplated that this microprocessor may be used to control theintegral pump/motor 1.

The cooling system may also be provided with an automotive thermostat inthe form of a thermostatically controlled valve 136 (shown in phantom inFIG. 6) for inhibiting the flow of fluid within the system until theoperating temperature of the fluid is reached. As is well known in theprior art, such valves 136 are normally closed. As the temperature ofthe fluid in the water jacket 102 increases, such valves are heated bythe heated fluid 104 and mechanically open to permit circulation of thefluid within the cooling system. The purpose of such valves is to permitthe fluid within the water jacket 102 to quickly reach operatingtemperature before fluid circulation begins. In prior art systemsemploying mechanical "water" (fluid) pumps which operate continuouslywhenever the engine is running, such valves selectively inhibit fluidflow. In a system according to the invention, valve 136 is optionalbecause fluid flow is controlled by actuation or deactuation of integralpump/motor 1. Control 128, for example, would not supply electricalpower to the stator assembly of integral pump/motor 1 until the fluid104 in the water jacket has reached operating temperature.

It is contemplated that the integral motor/pump 1 may be operated atfixed or variable speeds. For example, in fixed speed operation,integral pump/motor 1 would be activated at one or more fixed speeds ortorques simultaneously with fan motor 126 by electronic control 128selectively providing power thereto. Optionally, the particularoperating speed or torque of integral pump/motor 1 may be made dependenton various operating conditions of the automobile such as thetemperature of the heated fluid 104 and the cooled fluid 110, the airtemperature, the engine operating speed and/or the need to supply heatedfluid via the auxiliary flow. For example, integral pump/motor 1 may beselectively actuated in response to the need for heating of thepassenger compartment.

In variable speed/torque operation, the speed or torque of the integralpump/motor 1 is controlled and varied to meet the needs of theautomobile in response to the various operating conditions of theautomobile. For example, the control as disclosed in U.S. Pat. Nos.4,459,519 and 4,556,827, incorporated herein by reference, or asdisclosed in co-assigned, copending patent application Ser. No. 015,409,incorporated herein by reference, may be employed to control operationof integral pump/motor 1.

Although FIG. 6 illustrates integral pump/motor 1 in line between fluidline 112 and the water jacket 102, it is contemplated that it may belocated in any line of the cooling system and at any point along thefluid flow path.

In one mode of operation of the invention, it is contemplated that theintegral Pump/motor 1 may be operated after engine 100 has completed itsoperating cycle and has been turned off. For example, consider anautomobile engine that has operated for a period sufficient to permitthe cooling fluid to reach a stable operating temperature. When theengine is turned off after this operating period, heat from the engineblock continues to be transferred to the fluid in water jacket 102because the block is substantially hotter than the fluid 104. The heatedfluid 104 may migrate by convection flow into lines 106 and 114 andpossibly into pump/motor 1. As a result, the migrated fluid subjects thecooling system parts which it contacts to increased temperatures (atemperature spike) which, in turn, may result in damage and/or decreaseduseful life of the parts.

Operation of fan motor 126 alone after the engine operating period endsis well known in the prior art but fails to significantly reduce thetemperature spike to which cooling system parts are subjected because nofluid is circulating within the cooling system (other than a smallamount of migrating fluid flowing by convection). As a result, operationof fan motor 126 alone after the engine operating period only prevents atemperature spike within radiator 108. Some of the parts of the coolingsystem adjacent to the radiator 108 may be cooled because some of thecooled fluid may migrate as a result of convection flow into parts ofthe cooling system adjacent to the radiator 108. Prior art mechanical,automotive "water" pumps cannot solve the temperature spike problembecause such pumps can only operate when the engine operates.

By operating both the integral pump/motor 1 and fan motor 125 for ashort period after engine operation, heat build-up within the engineblock can be quickly dissipated throughout the cooling system andreleased to the air through radiator 108. In cooling systems in whichthe fluid volume has sufficient mass to absorb the heat buildup withinthe engine block without a significant temperature rise and without theneed for cooling, it may only be necessary to operate integralpump-motor 1 at a low speed or torque and not operate fan motor 126 atall after the engine 100 is turned off. Control 128, which would controlthe integral pump/motor 1 operation, constitutes power supply means forsupplying electrical Power to the stator assembly of integral pump/motor1 during and subsequent to operation of the automobile engine 100whenever the temperature of the fluid 104 is above a predeterminedtemperature (say 240°).

The above-described operation of the cooling system illustrated in FIG.6 constitutes a method of circulating fluid within a system such as acooling system of an automobile engine. By connecting line 114 to theinlet 120 and outlet 122 of integral pump/motor 1, a rotatable assembly20 including impeller 27 is located within extrusion 14 connected to thesystem. Control 128 provides electrical power to the stator assembly 11and thereby applies an electromagnetic field through the extrusion 14 toand around the rotatable assembly thereby to axially rotate the impeller27 and cause it to move fluid through the extrusion 14. Sensors 130 and132 sense the temperature of the fluid within the system and, inconjunction with control 128, selectively energize stator assembly 11 toselectively apply the electromagnetic field in response to thetemperature of the sensed fluid. The electromagnetic field may beapplied during and subsequent to operation of the automobile engine 100whenever the temperature of the fluid 104 is above a predeterminedtemperature.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained

As various changes could be made in the above constructions and methodswithout departing from the scope of the invention, it is intended thatall matter contained in the above description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. Apparatus for use in a cooling system to pumpfluid through the cooling system, said apparatus comprising:a housinghaving a continuous passage therethrough, the passage having an inletand an outlet adapted to be connected in the cooling system; firstmeans, located entirely within the passage in the housing and adapted torotate within the passage in the housing, for moving fluid from theinlet to the outlet; means located entirely within the inlet and theoutlet for supporting the first means for rotation about an axis coaxialwith the inlet and the outlet; means for sensing the temperature of thefluid in the cooling system; second means secured to the exterior of thehousing for applying an electromagnetic field through the housing to andaround the first means thereby to rotate the first means and cause it tomove fluid through the passage in the housing from the inlet to theoutlet to pump fluid through the cooling system; and means, responsiveto said temperature sensing means, for supplying electrical power tosaid second means.
 2. The apparatus of claim 1 wherein the coolingsystem is a cooling system of an automobile engine and wherein saidmeans for supplying electrical power includes power supply means forsupplying electrical power to said second means during and subsequent tooperation of the automobile engine whenever the temperature of the fluidis above a predetermined temperature.
 3. The apparatus of claim 1further comprising a heat exchanger adapted to release heat from thefluid to ambient air and a conduit for conducting the fluid between thecooling system and said heat exchanger and wherein said housing ispositioned in-line with said conduit.
 4. The apparatus of claim 3wherein the cooling system is a cooling system of an automobile enginehaving a fluid jacket and wherein said heat exchanger comprises aradiator for exchanging heat from the fluid to ambient air; and furthercomprising a fan for moving ambient air through the radiator, andwherein said means for supplying electrical power includes a powersupply supplying electrical power to said second means and said fanduring and subsequent to operation of the cooling system during periodsin which the temperature of the fluid is above a predeterminedtemperature.
 5. The apparatus of claim 4 further comprising means forbypassing said radiator to recirculate fluid between said fluid jacketand said first means.
 6. The apparatus of claim 1 wherein the coolingsystem is a cooling system of an automobile engine having a fluid jacketand wherein said cooling system comprises a radiator for exchanging heatfrom the fluid to ambient air; and further comprising a fan for movingambient air through the radiator, and wherein said means for supplyingelectrical power includes a power supply supplying electrical power tosaid second means and said fan during and subsequent to operation of thecooling system during periods in which the temperature of the fluid isabove a predetermined temperature.
 7. The apparatus of claim 6 furthercomprising means for bypassing said radiator to recirculate fluidbetween said fluid jacket and said first means.
 8. A method ofcirculating fluid within a system comprising the steps of:locating arotatable assembly including an impeller entirely within a housing whichis connected in the system, said housing having means located entirelywithin an inlet and an outlet of the housing for supporting therotatable assembly for rotation about an axis coaxial with the inlet andthe outlet; applying an electromagnetic field through the housing to andaround the rotatable assembly thereby to rotate the impeller and causeit to move fluid through the housing; sensing the temperature of thefluid in the system; and selectively performing said applying step inresponse to the temperature of the sensed fluid.
 9. The method of claim8 wherein the system is a cooling system of an automobile engine andwherein said applying step is selectively performed during andsubsequent to operation of the automobile engine whenever thetemperature of the fluid is above a predetermined temperature.
 10. Anapparatus for circulating fluid within a cooling system comprising:ahousing having an inlet and an outlet connected to the cooling system; arotatable assembly including an impeller entirely within the housing;means located entirely within the inlet and the outlet for supportingthe rotatable assembly for rotation about an axis coaxial with the inletand the outlet; a stationary assembly having a plurality of windingstages adapted to be energized to apply an electromagnetic field throughthe housing to and around the rotatable assembly thereby to rotate theimpeller and cause it to move fluid through the housing; means forsensing the temperature of the fluid in the system; and means forenergizing said winding stages as a function of the sensed fluidtemperature.
 11. Apparatus for circulating fluid in a cooling system ofthe type having a continuous passage having an inlet and an outlet forthe circulation of cooling fluid, said apparatus comprising:first meanslocated entirely inside the passage and freely rotatable inside thepassage for moving fluid through the passage; means located entirelywithin the inlet and the outlet for supporting the first means forrotation about an axis coaxial with the inlet and the outlet; secondmeans outside of the passage for applying an electromagnetic fieldthrough a portion of the passage, to and around the first means, torotate the first means inside the passage and cause it to move fluidthrough the passage from the inlet to the outlet; means for sensing thetemperature of the fluid in the passage; and means responsive to saidtemperature sensing means for supplying electrical power to said secondmeans to apply the electromagnetic field.
 12. Apparatus for coolingfluid heated by a source of heat, said apparatus comprising:means forcooling the fluid; conduit means for conducting fluid between the sourceof heat and the means for cooling; a housing having an inlet and outletconnected in the conduit means; first means, located entirely within andadapted to rotate within the housing, for moving fluid through thehousing from the inlet to the outlet; means located entirely within theinlet and the outlet for supporting the first means for rotation aboutan axis coaxial with the inlet and the outlet; means for sensing thetemperature of the fluid; second means secured to the exterior of thehousing for applying an electromagnetic field through the housing to andaround the first means thereby to rotate the first means and cause it tomove fluid through the housing from the inlet to the outlet; and meansresponsive to said temperature sensing means, for supplying electricalpower to said second means.